Multiple pass cargo inspection system

ABSTRACT

The present invention is a cargo inspection system, employing a radiation source, capable of scanning vehicles and/or cargo in a wide range of sizes, including conventional imaging areas as well as taller and bulkier enclosures at sufficiently optimal efficacy and overall throughput. In one embodiment, the present invention is a multiple pass inspection method for inspecting vehicles and their cargo, comprising a first pass scan, wherein said first pass scan includes moving a radiation source at a suitable scanning distance, rotating a radiation source at a suitable scanning angle, and moving said radiation source along an object under inspection.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present specification is a continuation of U.S. Pat. No. 8,170,177,filed on Nov. 22, 2010, which is a continuation of U.S. Pat. No.7,860,213, which is a continuation of U.S. Pat. No. 7,526,064, whichclaims priority from U.S. Provisional Patent Application No. 60/746,540,filed on May 5, 2006.

FIELD OF THE INVENTION

The present invention relates generally to a system and method forinspecting cargo, and more specifically, to improved methods and systemsfor detecting materials concealed within a wide variety of receptacles,vehicles, and/or cargo containers. In particular, the present inventionrelates to improved systems and methods for inspecting a wide range ofcargo sizes via a multiple pass, compact inspection system whilemaintaining optimal overall inspection throughput.

BACKGROUND OF THE INVENTION

Trade fraud, smuggling, and terrorism have increased the need fornon-intrusive inspection systems such as X-ray, gamma ray and linearaccelerator (LINAC)-based systems for inspecting cargo, trucks,passenger vehicles, and other transportation systems, which efficientlyprovide for the movement of commodities across borders. In addition,they provide opportunities for the inclusion of contraband items such asweapons, explosives, illicit drugs and precious metals. In particular,non-intrusive inspection systems are used in applications ranging fromcurbside inspection of parked vehicles to scanning in congested or hightraffic ports. The term port, while generally accepted as referring to aseaport, also applies to a land border crossing or any port of entry.

The size of the cargo or vehicle under inspection generally determinesthe size of the imaging system and thus, in general the bigger theobject under inspection, the bigger the inspection system.

With an increase in global commerce, port authorities require additionalsea berths and associated container storage space. Additional spacerequirements are typically met by the introduction of higher containerstacks, an expansion of ports along the coastline, or by moving inland.However, these scenarios are not typically feasible. Space is generallyin substantial demand and short supply. Existing ports operate under aroutine that is not easily modified without causing disruption to theentire infrastructure of the port. The introduction of new procedures ortechnologies often requires a substantial change in existing portoperating procedures in order to contribute to the port's throughput,efficiency, and operability.

With limited space available and a need to expand for increasedinspection performance, finding suitable space to accommodate additionalinspection facilities along the normal process route remains difficult.Moreover, systems incorporating the high energy X-ray sources, or linearaccelerators (LINAC), require either a major investment in shieldingmaterial (generally in the form of concrete formations or buildings) orthe use of exclusion zones (dead space) around the building itself. Ineither case, the building footprint is significant depending upon thesize of cargo containers to be inspected. Thus, the continual conflictis between making the system as small as possible while capable ofinspecting a varying range of objects, including large objects.

A typical size range for objects under inspection includes vehicles assmall as compact automobiles (or even smaller) to trucks carrying largecontainers. Thus, the object under inspection typically ranges from acompact automobile as small as 1.2 meters wide by 1.2 meters high to alarge truck that is up to 3 meters wide and 4.6 meters high.

Therefore, there is a need for a relatively compact inspection systemthat produces at least one image of objects of varying sizes. What isalso needed is a relatively compact inspection system that is capable ofproducing an image of an object in a single, first-pass image scan withno corner cut-off for smaller vehicles.

What is also needed is a relatively compact inspection system that iscapable of producing an image of a large object in a multiple pass imagescan in situations where a first pass image scan does not produce animage of a large object under inspection without corner cut off.

What is also needed is a relatively compact multiple pass inspectionsystem that maintains overall inspection throughput.

SUMMARY OF THE INVENTION

The present invention is a cargo inspection system, employing aradiation source, capable of scanning vehicles and/or cargo in a widerange of sizes, including conventional imaging areas as well as tallerand bulkier enclosures at sufficiently optimal efficacy and overallthroughput. In one embodiment, the present invention is a multiple passinspection method for inspecting vehicles and their cargo, comprising afirst pass scan, wherein said first pass scan includes moving aradiation source at a suitable scanning distance, rotating a radiationsource at a suitable scanning angle, and moving said radiation sourcealong an object under inspection.

The multiple pass inspection system for inspecting vehicles and theircargo comprises a radiation source having translational and rotationalmovement, a detector array having rotational movement, and a movablegantry. Optionally, the detector array is rotated about an axis at anangle equal to that of the radiation source, so that they are incontinual alignment. Optionally, the multiple pass inspection system ofclaim 4 wherein the radiation source and the detector array are mountedon the movable gantry.

In another embodiment, the present invention is a multiple passinspection method for inspecting vehicles and their cargo, comprising atleast a first pass scan and a second pass scan, wherein said first passscan includes moving a radiation source at a first suitable scanningdistance, rotating a radiation source at a first suitable scanningangle, and moving said radiation source along an object under inspectionand wherein said second pass scan includes moving a radiation source ata second suitable scanning distance, rotating a radiation source at asecond suitable scanning angle, and moving said radiation source alongan object under inspection.

In another embodiment, the present invention is a multiple passinspection method for inspecting vehicles and their cargo, comprising atleast a first pass scan, a second pass scan, and a third pass scan,wherein said first pass scan includes moving a radiation source at afirst suitable scanning distance, rotating a radiation source at a firstsuitable scanning angle, and moving said radiation source along anobject under inspection; wherein said second pass scan includes moving aradiation source at a second suitable scanning distance, rotating aradiation source at a second suitable scanning angle, and moving saidradiation source along an object under inspection; and wherein saidthird pass scan includes moving a radiation source at a third suitablescanning distance, rotating a radiation source at a third suitablescanning angle, and moving said radiation source along an object underinspection.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will beappreciated, as they become better understood by reference to thefollowing detailed description when considered in connection with theaccompanying drawings, wherein:

FIG. 1 is side perspective view of one embodiment of the multiple passinspection system of the present invention in a single pass useconfiguration, illustrating the radiation beam and scan area;

FIG. 2 is a top perspective view of one embodiment of the multiple passinspection system of the present invention, further depicting a typicalgantry transport system;

FIG. 3 a is a top perspective view of one embodiment of the multiplepass inspection system of the present invention, in a dual passconfiguration, further illustrating the scanning directions;

FIG. 3 b is a side perspective view of one embodiment of the multiplepass inspection system of the present invention, in a dual passconfiguration, further illustrating the radiation beam and scan area;

FIG. 4 is a depiction of the imaging area in one embodiment of themultiple pass cargo inspection system of the present invention,illustrating the imaging area resulting from a first pass lower positionscan in a multiple pass configuration;

FIG. 5 is a depiction of the imaging area in one embodiment of themultiple pass cargo inspection system of the present invention,illustrating the imaging area resulting from a second pass upperposition scan in a multiple pass configuration;

FIG. 6 is a depiction of the imaging area in one embodiment of themultiple pass cargo inspection system of the present invention,illustrating the imaging area resulting from a third pass centralposition scan in a multiple pass configuration;

FIG. 7 is a depiction of the imaging area in one embodiment of themultiple pass cargo inspection system of the present invention,illustrating the imaging area resulting from a first pass lower positionscan in a triple pass configuration, while inspecting a large truck;

FIG. 8 is a depiction of the imaging area in one embodiment of themultiple pass cargo inspection system of the present invention,illustrating the imaging area resulting from a second pass upperposition scan in a triple pass configuration, while inspecting a largetruck;

FIG. 9 is a depiction of the imaging area in one embodiment of themultiple pass cargo inspection system of the present invention,illustrating the imaging area resulting from illustrating the imagingarea resulting from a third pass central position scan in a multiplepass configuration, while inspecting a large truck;

FIG. 10 illustrates one embodiment of the multiple pass inspectionsystem of the present invention wherein the source may be verticallypositioned to completely scan an object under inspection in a singlepass; and

FIG. 11 illustrates another embodiment of the multiple pass inspectionsystem of the present invention wherein the source is verticallypositioned to completely scan an object under inspection in a dual passscan configuration, wherein the first pass is shown in FIG. 10.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed toward a system and method forinspecting cargo, and more specifically, to improved methods and systemsfor detecting materials concealed within a wide variety of receptacles,vehicles, and/or cargo containers. In particular, the present inventionis directed towards improved systems and methods for inspecting a widerange of cargo sizes via a multiple pass, compact inspection systemwhile maintaining optimal overall inspection throughput.

Reference will now be made to specific embodiments of the presentinvention. The embodiment described herein is not a general disavowal ofany one specific embodiment or used to limit the claims beyond themeaning of the terms used therein.

In one embodiment, the present invention is a multiple pass cargoinspection system, employing a radiation source, capable of scanningvehicles and/or cargo in a wide range of sizes, including conventionalimaging areas as well as taller and bulkier enclosures at sufficientlyoptimal efficacy and overall throughput. In one embodiment, theradiation source is an X-ray source. In another embodiment, theradiation source is a gamma ray source. In yet another embodiment, theradiation source is a linear accelerator (LINAC).

In one embodiment, the multiple pass inspection system of the presentinvention comprises a radiation source and detector array that canarranged and/or situated in various positions for scanning an objectunder inspection. In one embodiment, the radiation source is capable oftranslational movement along a y-axis in a three-dimensional coordinatesystem wherein the x-axis represents horizontal movement, the y-axisrepresents vertical movement, and the z-axis represents rotationalmovement. In another embodiment, the source is positioned on the y-axisand pivoted about the z-axis for optimal translational and rotationalmovement, respectively. Thus, the radiation source can be raised orlowered vertically and/or tilted or spun about an axis.

In one embodiment, the detector array employed in the multiple passcargo inspection system of the present invention can be rotated about anaxis in the same fashion as the radiation source. In one embodiment, thedetector array is rotated at an angle equal to that of the radiationsource, so that they are in continual alignment.

In one embodiment, the radiation source and detector package are mountedon a conventional gantry transport system such that both source anddetector array can be moved across the length of the inspection area.

In one embodiment of the multiple pass inspection system of the presentinvention, the inspection system operates and scans an entire objectunder inspection in a single pass. In this configuration, the gantrytransport system moves the radiation source once across the length ofthe inspection area, thereby illuminating the inspection area with adiverging fan beam of radiation.

In one embodiment, the inspection system operates and scans the objectunder inspection in a plurality of passes. Thus, the multiple pass cargoinspection system is capable of scanning objects of all sizes, includingvehicles and tall and/or bulky objects. In one embodiment, theinspection system is a dual pass scanning system. In a first pass, theradiation source and detector array are vertically positioned and tiltedin a first position to scan a lower portion of the inspection area andthus, object under inspection. In a second pass, the radiation sourceand detector array are vertically positioned and tilted in a secondposition to scan an upper portion of the inspection area, and thus,object under inspection.

For example, during a first pass, the radiation source and detectorarray are placed at a lower position, or at a lower point on the y-axisof the inspection system. The gantry system is then moved forward totravel across the distance of the length of the inspection area, andscans the lower portion of the inspection area. Upon reaching the end ofthe length of the inspection area, the radiation source and detectorarray are re-positioned to an upper scanning position, or at a higherpoint on the y-axis of the inspection system. During a second pass, thegantry system is moved backward to travel in a reverse direction acrossthe distance of the length of the inspection area, and scans the upperportion of the inspection area.

In another embodiment, the inspection system is a triple pass scanningsystem. The first and second pass scanning methods have been describedabove and are herein incorporated by reference. In one embodiment, inthe third pass scan, the radiation source and detector array are placedin a central position on the vertical y-axis. The third pass scan isusually initiated in situations where the first pass and second passscan are not sufficient to completely scan a tall or bulky object underinspection.

Optionally, when at the appropriate y-axis positions, the source can betilted or rotated about the z-axis.

In one embodiment, the third pass scan allows for multiple views atdifferent angles of an inspection area in which a threat item isotherwise obscured in a first pass scan or second pass scan. In oneexemplary scanning sequence, once the lower portion of the inspectionarea has been scanned with the radiation source in a forward direction,the radiation source is vertically and angularly positioned to thecentral point of the y-axis. The gantry is then moved in a reversedirection back to the starting point of inspection, thus scanning themid-region of the inspection area. The source is then moved to a highervertical position while at the start of the inspection area and moved ina forward direction through the inspection area, resulting in a scanimage of the upper portion of the inspection area.

It should be understood by those of ordinary skill in the art that in adual pass scan, scanning can begin from any vertical position and at anytilt of the radiation source and detector array. In one embodiment, tomaximize the overall throughput of the system, a second complete scan ofa second object under inspection can begin from the last position inwhich the source was at the completion of scanning for a first objectunder inspection. Each successive scan of an object under inspection canalso begin with the radiation source in its last scan position from theprevious object under inspection.

In addition, it should be understood by those of ordinary skill in theart that in a triple pass scan, the scanning sequence can be customizedby an operator depending upon the size of the inspection area and/or thelast scan position of the radiation source from the previous objectunder inspection, while still maintaining high throughput of theinspection system.

FIG. 1 is side perspective view of one embodiment of the multiple passinspection system of the present invention in a single pass useconfiguration, illustrating the radiation beam and scan area. In oneembodiment, multiple pass inspection system 100 comprises a radiationsource 105, for irradiating an object under inspection 110 with avertically divergent fan beam of radiation 115.

Radiation source 105 may be, but is not limited to, an X-ray source, alinear accelerator (LINAC), or a gamma radiation source. Preferably, theradiation source 105 includes a radio-isotopic source, an X-ray tube orany other source known in the art capable of producing beam flux andenergy sufficiently high to direct a beam to traverse the space throughan object under inspection to detectors at the other side. The choice ofsource type and its intensity and energy depends upon the sensitivity ofthe detectors, the radiographic density of the cargo in the spacebetween the source and detectors, radiation safety considerations, andoperational requirements, such as the inspection speed. One of ordinaryskill in the art would appreciate how to select a radiation source type,depending upon his or her inspection requirements. In one embodiment,where the object under inspection is a large sized container or car thathighly attenuates the X-ray beam, the radiation could be from an X-raytube operating at a voltage in substantial excess of 200 keV, and mayoperate in a region of approximately 4.5 MeV and even up to 10 MeV ormore.

In one embodiment, object under inspection 110 is a vehicle, truck, orother container for carrying cargo or passenger luggage or generalbelongings.

Multiple pass inspection system 100 further comprises detector array120, which is preferably positioned behind object under inspection 110and is used to detect radiation transmitted through the object underinspection 110. The detectors may be formed by a stack of crystals thatgenerate analog signals when X-rays impinge upon them, with the signalstrength proportional to the amount of beam attenuation in the objectunder inspection 110. In one embodiment, the X-ray beam detectorarrangement consists of a linear array of solid-state detectors of thecrystal-diode type. A typical arrangement uses cadmium tungstatescintillating crystals to absorb the X-rays transmitted through theobject under inspection and to convert the absorbed X-rays into photonsof visible light. Crystals such as bismuth germinate, sodium iodide orother suitable crystals may be alternatively used as known to a personof ordinary skill in the art. The crystals can be directly coupled to asuitable detector, such as a photodiode or photo-multiplier. Thedetector photodiodes could be linearly arranged, which throughunity-gain devices, provide advantages over photo-multipliers in termsof operating range, linearity and detector-to-detector matching. Inanother embodiment, an area detector is used as an alternative to lineararray detectors. Such an area detector could be a scintillating strip,such as cesium iodide or other materials known in the art, viewed by asuitable camera or optically coupled to a charge-coupled device (CCD).

As described above, during inspection, inspection system 100, and morespecifically radiation source 105 and detector array 120, is movedhorizontally across the length of the inspection area of inspectionsystem 100 such that the vertically extending fan beam 115 scans slicesof the object under inspection 110 across its overall length. Thus,multiple pass inspection system 100 is preferably mounted on a gantrytype transport system, as shown in FIG. 2, to allow for vertical,horizontal, and rotational movement of both the radiation source 105 anddetector array 120.

Now referring to FIG. 2, a top perspective view of one embodiment of themultiple pass inspection system of the present invention is shown,further depicting a typical gantry transport system 200, as describedwith respect to FIG. 1. Typical gantry-type transport systems arewell-known to those of ordinary skill in the art and thus will not bedescribed in detail herein. In one embodiment, the radiation source 205and detector array 210 are mounted on a gantry transport system 200 suchthat both source and detector array can be moved across the length(x-axis) of the inspection area in translational movement. In anotherembodiment, as described in further detail with respect to FIGS. 3 a and3 b, the radiation source and detector array are mounted on a gantrytransport system 200 such that both source and detector array can bemoved in a vertical direction (y-axis). In another embodiment, also asdescribed in further detail with respect to FIGS. 3 a and 3 b, theradiation source and detector array are mounted on a gantry transportsystem 200 such that both source and detector array can be moved in arotational direction (z-axis).

In one embodiment, radiation source 205 is located on the gantrytransport system and attached such that it is capable of bothtranslational and rotational movement. In one embodiment, radiationsource 205 is vertically displaced using a screw jack mechanism 215.Screw jack mechanisms are well-known to those of ordinary skill in theart and their operation will not be described herein. It should benoted, however, that the radiation source 205 is both raised and loweredusing the screw jack mechanism 215. In one embodiment, radiation source205 is positioned on a rotatable platform boom (not shown), allowing forrotational movement in a range of 0 to 90 degrees.

Referring back to FIG. 1, the radiation transmitted through the objectunder inspection 110 is attenuated to varying degrees by the objectunder inspection and its contents. The attenuation of the radiation is afunction of the density and atomic composition of the materials throughwhich the radiation passes. The attenuated radiation is detected andradiographic images of the contents of the object under inspection 110are generated. In one embodiment, the resultant images show the shape,size and varying densities of the contents.

Standard cargo containers are typically 20-50 feet long (6.1-15.2meters), 8-10 feet high (2.4-3.0 meters) and 6-8 feet wide (1.8-2.4meters). Air cargo containers and Unit Load Devices (ULDs), which areused to contain a plurality of pieces of luggage or other cargo to bestored in the body of an airplane, may range in size (length, height,width) from about 35×21×21 inches (0.89×0.53×0.53 meters) up to about240×118×96 1 inches (6.1×3.0×2.4 meters). Sea cargo containers aretypically about 40 feet long, 8 feet wide and 8 feet high.

In conventional inspection systems, to illuminate an object underinspection uniformly with an X-ray fan beam, the radiation source isplaced at a distance relatively far from the object under inspection.For example, but not limited to such example, to illuminate a cargocontainer with a height of about 8 feet (2.4 meters) with a verticalradiation beam emitted over an angle of about 24 degrees (+/−12 degreesfrom the central ray), the source should be about 19 feet (about 5.8meters) from the face of the cargo container. If the beam is emittedover an angle of about 120 degrees (+/−60 degrees from the central ray),however, the source may be placed about 2.5 feet (about 0.8 meters) fromthe face of the cargo container.

The multiple pass inspection system 100 of the present invention,however, is more compact and allows for the radiation source to beplaced closer to the object under inspection than with current systems.Thus, multiple pass inspection system 100 is compact and space-saving,and minimizes the probability of a decline in radiation intensity due tothe distance between the radiation source and the object underinspection.

Because the multiple pass inspection system 100 is compact, it iscapable of producing an image of an object under inspection of in awidth of up to 3 meters and a height of up to 2 meters in a single imagescan. In a single pass scan configuration, the gantry transport systemis moved once across the length of the object under inspection. Theangle of the fan beam is sufficient to illuminate the entire face of theobject under inspection 110. This single image scan, or first pass scan,provides an image with no ‘corner cut-off’ for all passenger cars, smallvans and buses, and for a typical check point is suitable for at least90% of total throughput.

When object under inspection is larger than a passenger vehicle,however, the single, first pass scan is only capable of producing animage of a lower portion of the object under inspection. Thus, aplurality of passes is required to fully illuminate and scan objectsunder inspection that are taller than a typical height of 2 meters.

FIG. 3 a is a top perspective view of one embodiment of the multiplepass inspection system of the present invention, in a dual passconfiguration, further illustrating the scanning directions. FIG. 3 b isa side perspective view of one embodiment of the multiple passinspection system of the present invention, in a dual passconfiguration, further illustrating the radiation beam and scan area.

Referring now to both FIGS. 3 a and 3 b, multiple pass inspection system300 employs a dual pass scan to completely irradiate and scan a largeobject under inspection 310. In operation, at the start of theinspection process, the radiation source 305 has a first verticalposition (not shown) and a first angular position 305 a such that itilluminates the lower portion of the object under inspection 310.Referring now to both FIGS. 3 a and 3 b, as gantry transport system 320moves horizontally in a first pass scan direction 301 a across length302 of the object under inspection 310, the radiation transmittedthrough the lower portion of the object under inspection 310 is detectedby the detector array 315 placed at a corresponding first angularposition 315 a so that it is in alignment with the radiation source 305placed at a first angular position 305 a.

On reaching the end of the length 302 of the object under inspection310, the source 305 is raised to a second vertical position (not shown)and a second angular position 305 b. Correspondingly, the detector array315 is moved into a second angular position 315 b so that it is inalignment with the radiation source 305 placed at a second angularposition 305 b. Thereafter, the gantry transport system 320 moveshorizontally, in a second pass scan reverse direction 301 b, and reachesthe inspection starting point while in the process scanning the upperportion of the object under inspection 310. Thus, by using the gantry'sreturn trip to perform a second scan, scanning time is minimized andsystem throughput is enhanced.

Where a ‘first pass’ scan in the forward direction is sufficient toimage the full height of the object, the reverse direction or returntrip scan is used for the subsequent vehicle under inspection thuseliminating the need to move the scanner back to the original startposition and maximizing the system throughput.

FIG. 4 is a depiction of the imaging area in one embodiment of themultiple pass cargo inspection system of the present invention,illustrating the imaging area resulting from a first pass lower positionscan in a multiple pass configuration. As shown in FIG. 4, after a firstpass lower position scan of an object under inspection, imaging area 405is obtained.

FIG. 5 is a depiction of the imaging area in one embodiment of themultiple pass cargo inspection system of the present invention,illustrating the imaging area resulting from a second pass upperposition scan in a multiple pass configuration. As shown in FIG. 4,after a second pass upper position scan of an object under inspection,imaging area 505 is obtained.

FIG. 6 is a depiction of the imaging area in one embodiment of themultiple pass cargo inspection system of the present invention,illustrating the imaging area resulting from a third pass centralposition scan in a multiple pass configuration. Thus, in situationswhere a dual pass scan is not sufficient to completely scan the objectunder inspection, it is possible to vertically position the radiationsource at varying heights to provide additional scans covering differentparts of the object under inspection.

As shown in FIG. 6, three passes are employed to completely scan a largeobject under inspection. Lower and upper scan positions 605 a and 605 band corresponding lower and upper detector positions 615 a and 615 b,are not sufficient to completely cover the entire volume of the objectunder inspection 610 (and effectively, the entire inspection volume orarea) and thus, leaves volume 620 not inspected. Thus, in order to scanvolume 620, the source is positioned at a central point 605 c on thevertical axis and detector array 615 is positioned at correspondingposition 615 c. This central radiation source point scanning featurealso allows multiple views at differing angles of the object underinspection, which in certain circumstances may help reveal a threat itemotherwise obscured in the image in a single or a dual image scan.

In operation of the triple pass inspection system, after the source hasscanned the object under inspection by moving forward along the x-axisand in the lower position, the source is vertically and angularlypositioned at a central point and is then moved in the reverse directionback to the starting point, scanning the central region of the objectunder inspection. The source is then moved in the upper position, andtranslated in the forward direction along the x-axis, scanning the upperportion of the object under inspection.

FIG. 7 is a depiction of the imaging area in one embodiment of themultiple pass cargo inspection system of the present invention,illustrating the imaging area resulting from a first pass lower positionscan in a triple pass configuration, while inspecting a large truck. Inone embodiment, radiation source 705 is placed at a first position 705 aon the gantry, lower on the y-axis. In addition, detector array 715 isplaced at a first position 715 a, so that the radiation source 705 anddetector array 715 are in alignment. Once the scan of the object underinspection, or large truck, is complete, lower imaging area 720 isobtained.

FIG. 8 is a depiction of the imaging area in one embodiment of themultiple pass cargo inspection system of the present invention,illustrating the imaging area resulting from a second pass upperposition scan in a triple pass configuration, while inspecting a largetruck. In one embodiment, radiation source 805 is placed at a secondposition 805 b on the gantry, lower on the y-axis. In addition, detectorarray 815 is placed at a second position 815 b, so that the radiationsource 805 and detector array 815 are in alignment. Once the scan of theobject under inspection, or large truck, is complete, upper imaging area820 is obtained.

FIG. 9 is a depiction of the imaging area in one embodiment of themultiple pass cargo inspection system of the present invention,illustrating the imaging area resulting from illustrating the imagingarea resulting from a third pass central position scan in a multiplepass configuration, while inspecting a large truck. In one embodiment,radiation source 905 is placed at a third position 805 c on the gantry,at the central point on the y-axis. In addition, detector array 915 isplaced at a second position 915 b, so that the radiation source 905 anddetector array 915 are in alignment. Once the scan of the object underinspection, or large truck, is complete, central imaging area 920 isobtained.

Thus, in one embodiment, in operation, the multiple pass cargoinspection system of the present invention may be varied to optimize theoverall throughput of the scanning system, including but not limited toa change in scan sequence. For example, but not limited to such example,if an object under inspection is scanned using any of the multiple passinspection methods, it is possible that at the end of the last pass thesource is in the upper position on the y-axis as described above andready to move forward on the x-axis. In this case, the subsequent objectunder inspection may be scanned beginning with the upper forwardposition, such that the gantry moves backward along the length of theobject under inspection to scan the upper portion of the object underinspection first. Thereafter, depending upon the scanning requirement,the source can be positioned at other positions to completely scan theobject under inspection. The invention, as described herein, is notlimited to such scan sequences and it should be understood by those ofordinary skill in the art that any number of scan sequences arepossible.

FIG. 10 illustrates one embodiment of the multiple pass inspectionsystem of the present invention wherein the source may be verticallypositioned to completely scan an object under inspection in a singlepass. If a single pass scan is sufficient to cover the entire volume ofthe object under inspection, the source 1005 can be verticallypositioned at a point that is most favorable to allow for the coverageof the entire object under inspection 1010.

FIG. 11 illustrates another embodiment of the multiple pass inspectionsystem of the present invention wherein the source is verticallypositioned to completely scan an object under inspection in a dual passscan configuration, wherein the first pass position is shown in FIG. 10.Thus, if a single pass can is not sufficient to cover the entire volumeof the object under inspection, the source 1105 can be verticallypositioned at a second point that is most favorable to allow forcoverage of the remainder of the object under inspection 1110—thatportion not scanned in the first pass—of the object under inspection1110. In this embodiment, an upper scan is not required since the lowerscan and central scan are sufficient to image the entire object underinspection 1110.

The above examples are merely illustrative of the many applications ofthe system of present invention. Although only a few embodiments of thepresent invention have been described herein, it should be understoodthat the present invention might be embodied in many other specificforms without departing from the spirit or scope of the invention. Forexample, other configurations of cargo, tires, tankers, doors, airplane,packages, boxes, suitcases, cargo containers, automobile semi-trailers,tanker trucks, railroad cars, and other similar objects under inspectioncan also be considered. Therefore, the present examples and embodimentsare to be considered as illustrative and not restrictive, and theinvention is not to be limited to the details given herein, but may bemodified within the scope of the appended claims.

I claim:
 1. A method of inspecting an object within an inspection zonewherein said inspection zone is defined by a radiation source on a firstside of said inspection zone and a detector array on an opposing side ofsaid inspection zone, comprising: Receiving the object, having a volume,in said inspection zone at a first position; Positioning said radiationsource to irradiate said object in a first scan; Re-positioning saidradiation source if said first scan does not irradiate the entire volumeof the object in the first scan; and Conducting a second scan with saidre-positioned radiation source.
 2. The method of claim 1, wherein saidradiation source is an X-ray source.
 3. The method of claim 1, whereinsaid radiation source is a gamma source.
 4. The method of claim 1,wherein said radiation source is a linear accelerator.
 5. The method ofclaim 1, wherein, when the radiation source is repositioned, thedetector array is rotated about an axis.
 6. The method of claim 5,wherein said rotation of the detector array aligns the detector arraywith the radiation source during operation of the radiation source. 7.The method of claim 1, wherein the radiation source is adapted toconduct the first scan of the object at a first vertical position and ata first scanning angle, and, after completion of said first scan,conduct the second scan at a second vertical position and at a secondscanning angle.
 8. The method of claim 7, wherein to move from the firstscanning angle to the second scanning angle, the radiation sourcerotates in a range of 0 to 90 degrees.
 9. The method of claim 7, whereinthe first scanning angle is different from said second scanning angle.10. The method of claim 1, wherein the first scan forms a first scanningregion, wherein the second scan forms a second scanning region, andwherein the first scanning region is different from the second scanningregion.
 11. The method of claim 1, wherein the first scan produces animage of the object, wherein said image includes a width of the objectof up to 3 meters and a height of the object of up to 2 meters.
 12. Themethod of claim 1, wherein the radiation source is repositioned if theobject is taller than 2 meters.
 13. The method of claim 1, wherein thedetector array is adapted to rotate about an axis and wherein saidrotation of the detector array aligns the detector array with theradiation source during the first scan and during the second scan.
 14. Amethod of inspecting an object, comprising: Receiving the object, havinga volume, in an inspection zone at a first position, wherein saidinspection zone is defined by a radiation source, in a first position,on a first side of said inspection zone and a detector array on anopposing side of said inspection zone; Activating said radiation sourceto irradiate said object in a first scan; Re-positioning said radiationsource if said first scan does not irradiate the entire volume of theobject in the first scan; and Conducting a second scan with saidre-positioned radiation source.
 15. The method of claim 14, wherein saidradiation source is at least one of an X-ray source, a gamma source, ora linear accelerator.
 16. The method of claim 14, wherein, when theradiation source is repositioned, the detector array is rotated about anaxis.
 17. The method of claim 16, wherein said rotation of the detectorarray aligns the detector array with the radiation source duringoperation of the radiation source.
 18. The method of claim 14, whereinthe radiation source is adapted to conduct the first scan of the objectat a first vertical position and at a first scanning angle, and, aftercompletion of said first scan, conduct the second scan at a secondvertical position and at a second scanning angle.
 19. The method ofclaim 18, wherein to move from the first scanning angle to the secondscanning angle, the radiation source rotates in a range of 0 to 90degrees.
 20. The method of claim 14, wherein the first scan produces animage of the object, wherein said image includes a width of the objectof up to 3 meters and a height of the object of up to 2 meters.
 21. Themethod of claim 14, wherein the radiation source is repositioned if theobject is taller than 2 meters.